All 18 1/2" barrels are non vent ribbed and have a ramped front sight with a matte finish. Each barrel comes with a Carlson choke tube, manufactured from 17-4 stainless steel except for the rifled choke tube models which are made from 304 high stress stainless steel, installed. All of our Remington 870 replacement barrels are threaded for the standard Rem Choke system. Enhance the versatility and performance of your shotgun with a Carlson's replacement shotgun barrel.